At present, a variety of irrigation apparatus are available for use in the watering of ornamental or farmed plants. Many of these apparatus are simply variations of traditional sprinklers, which have differing mechanisms for establishing spray patterns and flow rates which are appropriate to the type of plant for which the sprinkler is employed.
For certain shrubs, flowers (such as roses, etc.) and trees, it is important to be able to control both the amount of water which is supplied, but also in some cases, the supply of plant food or fertilizer and other chemical agents which are necessary for the sustained health and beauty of the plant.
The reader's attention is directed to several U.S. patents which disclose a more sophisticated apparatus for distributing water to plants. For example, U.S. Pat. No. 3,754,352, issued Aug. 28, 1973, to Bates discloses an above-ground, sealed water receptacle which distributes water to the soil underneath and allows the receptacle to be replenished when the water level dips below a certain elevation. In this case, the water receptacle is above ground, where it is susceptible to damage, or may impede the other landscaping activities which may be required near (in this instance) the tree which is being irrigated. In Bates, an air pipe is provided in the receptacle to allow the equalization of pressure so that water may flow.
In September of 1973, U.S. Pat. No. 3,755,966 was issued to Smith, disclosing a Deep Root Feeder and Tree Irrigator. The Smith apparatus teaches an elongated cannister which has a plurality of apertures at both ends and is filled with gravel and fertilizer pellets for the controlled feeding of the tree. The Smith apparatus relies on rainwater for its source of moisture, and by virtue of the construction at the top, is susceptible to clogging by debris such as leaves or other natural matter which may rest upon the device by the normal forces of nature. While similar to Bates in that moisture is introduced sub-surface, further improvements were made in the art with the issuance of U.S. Pat. No. 4,726,143, issued to Steinbeck on Feb. 23, 1988. Steinbeck was the first of these references to disclose a filter for the top of the canister for keeping out foreign debris, and a cylinder with more than one space or compartment for preventing the waste of fertilizer by exiting the top of the device in the event of, for example, flooding. Again, relying on rainwater rather than a certain source of moisture, the Steinbeck apparatus was the first reference found which began to address the practical problem of clogging of the upper end by debris, which is inherent in such devices.
The first reference found which disclosed an apparatus which also functioned to facilitate the introduction of oxygen into the plant root area was U.S. Pat. No. 3,821,863, issued Jul. 2, 1974 to Chan, and which provided compartments void of anything which would obstruct the ventilation of the lower section of the tapered container portion.
On May 25, 1993, U.S. Pat. No. 5,212,905 was issued to Philoctete for a Plant Watering Device disclosing a self-contained reservoir placed around a seedling plant, and which distributes water in two ways. When the water reservoir is full, a plurality of apertures at the upper end of the device releases water. Once the water level falls below the apertures, a drip nozzle continues to allow water to be distributed to the plant. In the Philoctete apparatus, after a plant reaches a certain size, the apparatus is no longer useful, making the device applicable only to seedling plants. Application for larger plants requires a different scheme in order to justify the expense of dedication of irrigation parts to a certain plant.
Consequently, the prior art which pertains to irrigating shrubs and trees has centered around food, oxygen and deep watering, but only in a piecemeal fashion. It is clear that the introduction of water, food, and oxygen at the proper depth is key, but the prior art has not met the whole of these needs to any great extent. Further, where nutrients are introduced, as in Smith or Steinbeck, significant time and labor is required to "re-charge" the device with fertilizer, taking away from the potential ease of automatic watering and feeding.
What is needed is an irrigation apparatus that efficiently distributes measured amounts of nutrients and water at the proper depth, is unobtrusive to the surface to resist damage, prevents clogging while allowing the free exchange of air and moisture, and which is easily maintained for rapid "re-charging" with plant food.